Split the project package in two: internal and interface.
This way only interface package has to be imported by user RTL.
Cleaned up a bit the simulation scripts.
Merge branch 'master' of https://github.com/jaruiz/ion

Conflicts:
	sim/modelsim/ion_core/ion_core_tb.do
	sim/modelsim/ion_core/ion_core_tb_wave.do
	sim/modelsim/ion_cpu/ion_cpu_tb.do
	sim/modelsim/ion_cpu/ion_cpu_tb_wave.do
	src/rtl/common/ion_internal_pkg.vhdl